Tuesday, October 7, 2008

Human evolution over or speeding up?

"Compare and contrast..." goes the start of many an exam question. Well, in catching up on my reading of blogs and news media, I have just come across an interesting pair of articles, ripe for the compare-and contrast-treatment:

How We Evolve by BENJAMIN PHELAN from Seed magazine, which claims that human evolution has sped up recently.

I will leave it to you the reader to work through the two articles and do your own "compare-and-contrast" assessment, but my own inclination is to side with Phelan rather than Jones on this.

In fact, it seems odd that Jones is still publishing articles like this, because he has been making this point for a decade or more and this is nothing new in the Telegraph article. When Jones first started saying human evolution is over, we were still in the history-is-over epoch, before 9/11, the Afghanistan and Iraq wars and the reassertion of Russian military and political power.

Even back then, I found several problems Jones' argument:

It reeks of first-world complacency, when infant mortality is still so high in the Third World and populations are still being decimated by HIV, TB and malaria.

Even if the vast majority of people survive to reproductive age, the fact that even a small number do not is still enough to drive evolution. As Darwin said: "A grain in the balance will determine which individual shall live and which shall die, -- which variety or species shall increase in number, and which shall decrease, or finally become extinct."

Even if the vast majority of people survive to reproductive age, in an era of contraception and family planning, not all will have the same number of children. Any genetic difference that underlies this differential in reproductive success will still be the subject of natural selection. It’s a matter of speculation what affect fertility control will have on the human gene pool. When procreation is a matter of choice, rather than an inevitable consequence of passion, perhaps there will be a selective pressure for children to become steadily more manageable: if your first child is a terror, you might choose not to have any more! And conversely, whatever genes make people like children will be selected for!

If evolution is defined as any change in the frequency of alleles in the human gene pool, then lifting the selective pressure against what would, before modern society and medicine, have been deleterious genes or combinations of genes, then we are clearly in an era of massive evolutionary change. For example, is it really plausible that the rise in Caesarian sections is not having some effect on the distribution of genes underlying pelvic anatomy or determining the likelihood of other complications during labour?

Add to that the arguments in the Seed article and in the articles cited therein, and I see little or no cogency in Jones' arguments. I will leave the last word to Darwin:

“But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man's feeble efforts, as the works of Nature are to those of Art.”

The publication in 1859 of Charles Darwin’s masterpiece The Origin of Species changed forever the way we think about life on Earth, but also the human condition. One hundred and fifty years later—and 200 years after his birth—Darwin's big idea has never been more relevant or more challenging. The Rough Guide to Evolution provides a readable introduction to evolution and its influence on almost all aspects of human thought.

Features include:

The life and works of Darwin.

The growth of evolutionary thought.

The evidence for evolution.

The evolutionary history of life on Earth and human evolution

How Darwin’s breakthrough is still denied by creationists.

The wider impact of evolutionary thinking on science and society—from physics and cosmology to Guinness ads and The Simpsons.

The Rough Guide to Evolution has been distributed to 6000 undergraduate students through the Great Read at Birmingham initiative.

About Me

I obtained my medical education from the University of Cambridge and the London Hospital Medical College. I completed my specialist training as a medical microbiologist at Bart’s Hospital in London. In the mid-1990s, while completing a PhD in molecular bacteriology at Imperial College, London, I led a team of students to victory in the national quiz show University Challenge. In 1999, I took up a chair in microbiology at Queen’s University Belfast before moving to a chair in Birmingham in 2001. I took up my current position in April 2013